An image forming apparatus conveys a medium (hereinafter referred to as “sheet”) such as paper and forms an image on the sheet. The image forming apparatus is provided with a register roller for aligning the front end part of the sheet and a conveyance roller for conveying the sheet towards the register roller. The conveyance roller abuts the front end of the sheet against the stopped register roller. The conveyance roller deflects the sheet to align the front end of the sheet. However, if the skew amount of the sheet in the conveyance direction is too large, there is a possibility that the register roller cannot align the front end of the sheet.